Administration of a single dose of 300 IU of human chorionic gonadotropin seven days after the onset of estrus improves pregnancy rate in dairy goats by an unknown mechanism.

This study examined the effects of exogenous hCG administration on ovarian function and pregnancy rates in estrous-induced dairy goats during the transition into the breeding season. Eighty-six Toggenburg does received 60 mg of medroxyprogesterone acetate intravaginal sponge for 6 d plus 200 IU of equine chorionic gonadotropin and 30 µg of d-cloprostenol i.m. 24 h before sponge removal, and were then bred for 96 h. Seven days (D7) after first mating the does received either 1 mL of saline (the control group, n = 43) or 300 IU of hCG (the hCG-treated group, n = 43) i.m. Transrectal ovarian ultrasonography (B-mode and color Doppler) was performed on D7, D13, D17, and D21 and ultrasonographic pregnancy detection on D30. Pregnancy rate was higher (P < 0.05) in hCG-treated goats (90.7%; 39/43) than that in control animals (74.4%; 32/43). Accessory luteal structures (ALSs) were detected in 46.5% (20/43) of hCG-treated does. All hCG-treated does that had ALSs and 82.6% of goats without ALS post-treatment remained pregnant. The total luteal area increased (P < 0.05) from D7 to D13 in pregnant animals of both groups, whereas mean vascular area declined (P < 0.05) by D21 in all nonpregnant does. Serum progesterone concentrations increased (P < 0.05) on D21 in pregnant goats of both groups, but they were related to changes in luteal tissue content only in control does throughout the present study. Mean daily numbers of small- and medium-sized antral follicles decreased (P < 0.05) only in pregnant animals of both groups with a decline in medium follicle numbers occurring earlier in hCG-treated (D13) compared with control does (D17). To summarize, a single dose of hCG given on D7 after estrus was followed by a decrease in the number of medium-sized antral follicles in gestating hCG-treated does, induced the formation of ALSs in ~47% of all hCG-treated does, and significantly increased the pregnancy rate in estrous-induced Toggenburg goats in the transition to the breeding season.

Exogenous progestogens differentially alter gene expression of immature cumulus-oocyte complexes in sheep.

This study evaluated the role of progesterone (P4) and medroxyprogesterone acetate (MAP) on the molecular status of immature cumulus-oocyte complexes (COCs) and the implications for oocyte quality in sheep. The number of viable COCs per ewe and the rate of COCs screened for developmental competence by brilliant cresyl blue positive (BCB+) were similar (P > 0.05), respectively, across treatments (P4: 7.7 ± 0.7 and 4.7 ± 1.2; MAP: 5.7 ± 1.0 and 3.5 ± 2.3; and control: 5.7 ± 1.1 and 3.6 ± 2.4). The COCs' gene expression was altered by exogenous progestogens compared with the control group: markers of steroidogenic pathway (FSH receptor [FSHr], LH receptor [LHr], and estradiol receptor α) and of quality (zygote arrest 1, growth differentiation factor 9, and B-cell lymphoma 2) were in abundance in P4 (P < 0.05). In addition, reelin protein (RELN) was downregulated, and Bcl-2 was upregulated in MAP (P < 0.05). In the P4 vs MAP comparison, FSHr, LHr, and RELN genes were upregulated (P < 0.05) in the P4 group. In conclusion, P4 and MAP promoted dissimilar effects on transcriptome profiling of immature BCB-selected COCs, possibly due to the differences in the chemical structure of progestogens and concentrations of serum P4. Exogenous P4 impacted positively on the profile of genes related to oocyte quality.

Differential expression of LHCGR and its isoforms is associated to the variability in superovulation responses of Gir cattle.

The aim of this study was to evaluate the pattern of expression of LHCGR isoforms in Gir heifers characterized as good (10.3 ±â€¯1.2 ova/embryos per flush, n = 5) or poor responders (1.1 ±â€¯0.3 ova/embryos per flush, n = 5) to superovulation protocols. In both groups, an adapted ultrasound-guided follicular aspiration system was used to collect granulosa cells from 8 mm follicles formed either during a synchronized, non-stimulated follicular wave (no stimulation control, NS) or on the fourth day of a superovulation protocol (SOV) induced with 200 IU of pFSH. The recovered follicular fluid was centrifuged and granulosa cells were washed with NaCl 0.9% and kept in RNAlater®. RNA extraction was performed using a commercial RNeasy Micro Kit and eluted samples were quantified and reverse transcribed using the commercial Superscript III kit. cDNA samples were amplified by real-time PCR using a primer to target LH/hCG receptor gene - not selective for LHCGR isoforms (total LHCGR) - and four sets of isoforms selective primers (S1, S10, S10 + 11, and S11). Analyses were performed using the REST software and expression levels are shown as mean ± SEM. Under physiological conditions (NS), poor responders had a higher expression of total LHCGR (4.9 ± 1.7 fold-change, P < 0.01) as well as isoforms S10, S11 and S10 + 11, compared to good responders. In both phenotypes, superovulation down-regulated total LHCGR expression (-0.5 ± 0.2 and -0.9 ± 0.0 for good and poor responders, respectively; P < 0.05). However, in poor responders the exogenous FSH treatment up-regulated the S10 (2.4 ± 2.0; P < 0.05), S10 + 11 (3.8 ± 3.2; P < 0.01), and S1 isoforms (1.8 ± 1.3; P < 0.05), compared to good responders We conclude that down-regulation of total LHCGR, associated to up-regulation of their inactive isoforms, may have compromised follicle development and thus contributed to the low efficiency of superovulation in heifers with a poor responder phenotype.

Intrafollicular oestradiol production, expression of the LH receptor (LHR) gene and its isoforms, and early follicular deviation in Bos indicus.

The aim of the present study was to characterise the roles of intrafollicular oestradiol production and granulosa cell (GC) expression of the LH receptor (LHR) gene and its isoforms during follicular deviation in Bos indicus. Follicular wave emergence was synchronised in heifers from a Bos taurus dairy (Holstein; n=10) and a B. indicus dairy breed (Gir; n=10). Follicles were aspirated individually at sizes corresponding to the periods of predeviation, deviation and postdeviation. Intrafollicular oestradiol (IF-E2) and progesterone (IF-P4) concentrations were determined in the follicular fluid (FF) by radioimmunoassay, and relative expression of P450 aromatase (CYP19A1) and LHR forms was evaluated in GC using real-time quantitative-polymerase chain reaction. Despite differences in the size of the dominant follicle at deviation, changes in CYP19A1 expression and IF-E2 concentrations were similar in follicles of the same diameter in both breeds. A peak in total LHR expression occurred after follicular deviation in association with low expression of LHR isoforms. The results suggest that regulation of LHR function by sequential changes in the expression pattern of LHR isoforms may play a role in the early deviation of the dominant follicle, as observed in B. indicus breeds.

Polymorphisms and alternative splicing of the luteinizing hormone receptor of dairy cattle.

The aim of this study was to screen for variability in the luteinizing hormone/choriogonadotropin receptor (LHCGR) and to determine the occurrence of LHCGR mRNA isoforms in two dairy breeds of cattle. Granulosa cells from dominant ovarian follicles were recovered from 16 Gir and 16 Holstein cows, and total RNA was extracted. Complementary DNA was synthesized and PCR was used to generate amplicons for sequencing. Chromatograms were evaluated, and multiple sequences were aligned and analyzed for the presence of polymorphisms, allele frequency, polymorphic information content (PIC), and Hardy-Weinberg equilibrium (HWE). Twenty-one single nucleotide polymorphisms (SNPs) were identified in LH receptor mRNA. Seventeen SNPs were identified in Gir cattle (seven exclusively), and 14 were found in Holstein cattle (four exclusively). Seven of the 21 polymorphisms found did not alter which amino acid was translated. Eight SNPs caused a change to an amino acid in a different chemical group. Classification of SNPs according to PIC values identified 12 as being highly informative in Gir cattle and five in Holstein. Eight SNPs deviated from HWE in Gir compared with 11 in Holstein, and eight in both breeds. Two isoforms were also identified, one in exon 1, which lacks 30 nucleotides beginning at position 118, and the other in exon 10. Taken together, these data show that LHCGR in dairy cattle breeds has a high frequency of polymorphism and exists in multiple isoforms resulting from alternative splicing.

Occurrence and characteristics of residual follicles formed after transvaginal ultrasound-guided follicle aspiration in cattle.

Ultrasound-guided transvaginal follicle aspiration is used to recover cumulus-oocyte complexes (for IVF) and to synchronize follicular wave emergence (ablation of dominant follicle). Although aspirated follicles are generally supposed to undergo immediate atresia, there are indications that they may remain active. The objective was to evaluate the occurrence and characteristics of residual follicles (RF) after transvaginal follicle aspiration in cattle. Ovarian follicular wave emergence was synchronized in Holstein cows (N = 13) in the presence (groups 1 and 3) or absence (groups 2 and 4) of norgestomet implants. The largest follicle was aspirated at a diameter of 8 mm (groups 1 and 2) or 12 mm (groups 3 and 4). Ovarian follicles were visualized (transrectal ultrasonography) every 12 h after wave emergence. Follicular fluid samples were collected from the largest follicle and from the ensuing RF and concentrations of estradiol and progesterone were determined. After aspiration, 73.2% (52/71) of the follicles refilled with fluid, and a new antrum was detected 12 to 24 h later. Norgestomet did not affect (P > 0.05) RF occurrence or diameter, but in RF from group 4, concentrations of estradiol decreased (-530.7 ± 133.9 ng/mL; P < 0.01) whereas progesterone increased (+429.6 ± 171.7 ng/mL; P < 0.05) relative to preaspiration. In RF, there were three steroidogenesis patterns: (1) high estradiol concentration and high estradiol:progesterone ratio (estradiol-active RF); (2) low estradiol, but high progesterone concentrations (luteinized RF); and (3) low estradiol and low progesterone concentrations (inactive RF). Estradiol-active RF were more likely (P < 0.05) from follicles with high estradiol concentrations (regardless of diameter). In conclusion, fluid-filled structures (RF) with variable steroid production patterns are frequently formed after ultrasound-guided follicle aspiration. The occurrence and features of these RF depended on the diameter and status of these follicles before aspiration.

Pregnancy rates and corpus luteum-related factors affecting pregnancy establishment in bovine recipients synchronized for fixed-time embryo transfer.

The objective was to investigate the influence of corpora lutea physical and functional characteristics on pregnancy rates in bovine recipients synchronized for fixed-time embryo transfer (FTET). Crossbred (Bos taurus taurus x Bos taurus indicus) nonlactating cows and heifers (n=259) were treated with the following protocol: 2mg estradiol benzoate (EB) plus an intravaginal progesterone device (CIDR 1.9g progesterone; Day 0); 400 IU equine chorionic gonadotropin (eCG; Day 5); prostaglandin F(2alpha) (PGF(2alpha)) and CIDR withdrawal (Day 8); and 1mg EB (Day 9). Ovarian ultrasonography and blood sample collections were performed on Day 17. Of the 259 cattle initially treated, 197 (76.1%) were suitable recipients; they received a single, fresh, quality grade 1 or 2 in vivo-derived (n=90) or in vitro-produced (n=87) embryo on Day 17. Pregnancy rates (23 d after embryo transfer) were higher for in vivo-derived embryos than for in vitro-produced embryos (58.8% vs. 31.0%, respectively; P<0.001). Mean (+/-SD) plasma progesterone (P(4)) concentration was higher in cattle that became pregnant than that in nonpregnant cattle (5.2+/-5.0 vs. 3.8+/-2.4 ng/mL; P=0.02). Mean pixel values (71.8+/-1.3 vs. 71.2+/-1.1) and pixel heterogeneity (14.8+/-0.3 vs. 14.5+/-0.5) were similar between pregnant and nonpregnant recipients (P>0.10). No significant relationship was detected between pregnancy outcome and plasma P(4), corpus luteum area, or corpus luteum echotexture. Embryo type, however, affected the odds of pregnancy. In conclusion, corpus luteum-related traits were poor predictors of pregnancy in recipients. The type of embryo, however, was a major factor affecting pregnancy outcome.

Time correlation function in systems with two coexisting biological species.

We study a stochastic lattice model describing the dynamics of coexistence of two interacting biological species. The model comprehends the local processes of birth, death, and diffusion of individuals of each species and is grounded on interaction of the predator-prey type. The species coexistence can be of two types: With self-sustained coupled time oscillations of population densities and without oscillations. We perform numerical simulations of the model on a square lattice and analyze the temporal behavior of each species by computing the time correlation functions as well as the spectral densities. This analysis provides an appropriate characterization of the different types of coexistence. It is also used to examine linked population cycles in nature and in experiment.

Frequência de enteroparasitas em amostras fecais de cães e gatos dos municípios do Rio de janeiro e Niterói / Frequency of enteric parasites in fecal samples of dogs and cats in Rio de Janeiro and Niterói

Foram analisadas 252 amostras de fezes de cães e gatos provenientes dos municípios do Rio de Janeiro e Niterói no período de 1999 a 2000. Foram 212 (84,12

Freqüência de enteroparasitas em amostras fecais de cães e gatos dos municípios do Rio de Janeiro e Niterói

Foram analisadas 252 amostras de fezes de cães e gatos provenientes dos municípios do Rio de Janeiro e Niterói no períodode 1999 a 2000. Foram 212 (84,12%) amostras de cães e 40 (15,87%) de gatos. Do total de amostras examinadas 81(32,14%), foram positivas para pelo menos uma espécie de parasita. Dos 212 exames de material fecal canino, 70 (33,01%)estavam positivos e de felinos 11 (27,5%). As infecções mistas foram observadas em 10 amostras caninas (14,28%) e quatrofelinas (36,36%). Nas amostras caninas, ovos de ancilostomídeos foram os mais encontrados em 43 (61,43%) amostras,enquanto os coccídeos foram mais freqüentemente observados nas fezes de felinos em três (27,27%) amostras. Quanto àidade dos animais, 37 (52,85%) amostras positivas eram provenientes de animais com mais de 1 ano de idade, indicandoprovável vermifugação dos filhotes, enquanto nos gatos a faixa etária mais parasitada foi de menos de seis meses, com 7(63,63%) positivos.